Generally, a touch display device can include a display panel, a touch panel and related control circuits. A conventional in-cell touch display device can divide into a plurality of blocks; each block may include a plurality of scanning lines. For each block, display scanning and touch scanning can be done sequentially during a scanning cycle. After the display scanning and the touch scanning of one block finish, the display scanning of a next block starts. During a conventional display scanning process of each block, the scanning lines are sequentially scanned from a first scanning line to a last scanning line. When the last scanning line is scanned, the display scanning finishes and the touch scanning process of the block starts. However, for each block, the display scanning always stops at the same last scanning lines, which is bad for continuity of display.